Plants need nitrogen in the form of ammonium if they are to grow.
Plants need nitrogen in the form of ammonium if they are to grow. In the case of a great many cultivated plants, farmers are obliged to spread this ammonium on their fields as fertiliser. Manufacturing ammonium is an energy-intensive and costly process – and today’s production methods also release large amounts of CO2.
However, a handful of crops replenish their own supply of ammonium. The roots of beans, peas, clover and other legumes harbour bacteria (rhizobia) that can convert nitrogen from the air into ammonium. This symbiosis benefits both the plants and the rhizobia in an interaction that scientists had until now seen as relatively straightforward: the bacteria supply the plant with ammonium; in return, the plant provides them with carbonaceous carboxylic acid molecules.
A surprisingly complex interaction
Under the leadership of Beat Christen, Professor of Experimental Systems Biology, and Matthias Christen, a scientist at the Institute for Molecular Systems Biology, ETH researchers have now succeeded in demonstrating that the plant-bacteria interaction is in fact surprisingly complex. Along with carbon, the plant gives the bacteria the nitrogen-rich amino acid arginine.
Read more at ETH Zurich
Photo: Rhizobia (in blue) in the roots of a plant. The brown structures are plant proteins (coloured electron microscope image). (CREDIT: ETH Zurich / Anne-Greet Bittermann)
